Abuse of addictive drugs leads to compromise of the immune system in both animals and humans studied in vivo and in vitro. The basic mechanisms for this modulation of the immune system are based on both direct interaction of the drugs with the immune cells or on the drug's action in the neuroendocrine system with subsequent action on the immune system by neuroendocrine secretions. Completing the cycle, the immune system can provide feedback control of the neuroendocrine system, thus forming a potent homeostatic loop linking such desperate elements as behavior and resistance to infection in a single network. The expertise for studying such a multi-component grid comes from many areas of experimental biology including pharmacology, molecular biology, immunology and the neurosciences. It is therefore proposed to hold a satellite meeting, in conjunction with the 1995 Neurosciences meeting (San Diego), to discuss the functioning of the neuro-immune-endocrine axis. The twin focal points of the meeting will be: 1. the use of drugs of abuse as informative agents to stress this system; and 2. the effect of the drug-induced immunomodulation on resistance to infection. The types of studies to be presented will include both demonstrations of primary mechanisms of action of the drugs, both direct and indirect via secondary hormonal secretion, as well as model systems of bacterial and viral infections which are modulated by drug use. In the latter category, in vivo models of HIV infection will be examined for modulatory effects of drugs. Also, a panel discussion is proposed to examine the question of why recent AIDS epidemiological studies find little effect of street drugs on survivability and quality of life while animal models and in vitro human studies predict a large deleterious effect. Since many public health decisions are based on animal models and in vitro results, it is important to know why these methods are at such great variance with the epidemiological results in this singularly important case. A second aim of this meeting is to educate the next generation of scientists for this field. Few educational programs have the range of expertise on drugs of abuse which will be encompassed by this meeting. Finally, papers from this meeting will be published in a timely manner by Plenum Press, which published books from 3 of the 4 previous meetings in this series.